Rubella, also known as German measles or three-day measles, is a vaccine-preventable viral infection that is often mild, causing a pink rash that starts on the face and lasts about three days, alongside swollen lymph nodes and joint pain. The most serious risk is infection during early pregnancy, which can lead to miscarriage or congenital rubella syndrome (CRS), resulting in cataracts, deafness, and heart and brain defects. Spread through airborne coughs, the disease has no specific treatment, but a single dose of the MMR vaccine is over 95% effective at preventing it. While about 100,000 cases of CRS occur globally each year, vaccination has been so successful that the World Health Organization declared the Americas free of rubella transmission in April 2015. First described by German physicians in 1814—hence the name "German measles"—rubella remains a target for worldwide elimination efforts.